linux-toradex.git/arch/arm/kernel/vmlinux.lds.S, branch v3.3.5

ARM: 7320/1: Fix proc_info table alignment

2012-02-09T16:25:37+00:00

With an admittedly exotic choice of configuration options
(CC_OPTIMIZE_FOR_SIZE, THUMB2, some other size-minimizing ones)
and compiler, the proc_info table can end up being misaligned,
and the kernel being unbootable (Error: unrecognized/unsupported
processor variant).

Forcing the alignement to 4 bytes in the linker script fixes the
issue.

Signed-off-by: Marc Zyngier 
Signed-off-by: Russell King

ARM: 7290/1: vmlinux.lds.S: align the exception fixup table to a 4-byte boundary

2012-01-23T10:20:04+00:00

The exception fixup table is currently aligned to a 32-byte boundary.
Whilst this won't cause any problems, the exception_table_entry
structures contain only a pair of unsigned longs, so 4-byte alignment
is all that is required. If the table was walked from start to end,
cacheline alignment may bring some performance benefits, but since a
binary search is used, the access pattern is random and will not benefit
from a stricter alignment.

Acked-by: Nicolas Pitre 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: 7289/1: vmlinux.lds.S: do not hardcode cacheline size as 32 bytes

2012-01-23T10:20:04+00:00

The linker script assumes a cacheline size of 32 bytes when aligning
the .data..cacheline_aligned and .data..percpu sections.

This patch updates the script to use L1_CACHE_BYTES, which should be set
to 64 on platforms that require it.

Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: idmap: populate identity map pgd at init time using .init.text

2011-12-06T14:04:14+00:00

When disabling and re-enabling the MMU, it is necessary to take out an
identity mapping for the code that manipulates the SCTLR in order to
avoid it disappearing from under our feet. This is useful when soft
rebooting and returning from CPU suspend.

This patch allocates a set of page tables during boot and populates them
with an identity mapping for the .idmap.text section. This means that
users of the identity map do not need to manage their own pgd and can
instead annotate their functions with __idmap or, in the case of assembly
code, place them in the correct section.

Acked-by: Dave Martin 
Reviewed-by: Catalin Marinas 
Tested-by: Lorenzo Pieralisi 
Signed-off-by: Will Deacon

Merge branch 'misc' into for-linus

2011-10-25T07:19:59+00:00

Conflicts:
	arch/arm/mach-integrator/integrator_ap.c

ARM: 7017/1: Use generic BUG() handler

2011-10-17T08:13:41+00:00

ARM uses its own BUG() handler which makes its output slightly different
from other archtectures.

One of the problems is that the ARM implementation doesn't report the function
with the BUG() in it, but always reports the PC being in __bug(). The generic
implementation doesn't have this problem.

Currently we get something like:

kernel BUG at fs/proc/breakme.c:35!
Unable to handle kernel NULL pointer dereference at virtual address 00000000
...
PC is at __bug+0x20/0x2c

With this patch it displays:

kernel BUG at fs/proc/breakme.c:35!
Internal error: Oops - undefined instruction: 0 [#1] PREEMPT SMP
...
PC is at write_breakme+0xd0/0x1b4

This implementation uses an undefined instruction to implement BUG, and sets up
a bug table containing the relevant information. Many versions of gcc do not
support %c properly for ARM (inserting a # when they shouldn't) so we work
around this using distasteful macro magic.

v1: Initial version to replace existing ARM BUG() implementation with something
more similar to other architectures.

v2: Add Thumb support, remove backtrace whitespace output changes. Change to
use macros instead of requiring the asm %d flag to work (thanks to
Dave Martin )

v3: Remove old BUG() implementation in favor of this one.
Remove the Backtrace: message (will submit this separately).
Use ARM_EXIT_KEEP() so that some architectures can dump exit text at link time
thanks to Stephen Boyd  (although since we always
define GENERIC_BUG this might be academic.)
Rebase to linux-2.6.git master.

v4: Allow BUGS in modules (these were not reported correctly in v3)
(thanks to Stephen Boyd  for suggesting that.)
Remove __bug() as this is no longer needed.

v5: Add %progbits as the section flags.

Signed-off-by: Simon Glass 
Reviewed-by: Stephen Boyd 
Tested-by: Stephen Boyd 
Signed-off-by: Russell King

ARM: fix vmlinux.lds.S discarding sections

2011-09-20T22:42:31+00:00

We are seeing linker errors caused by sections being discarded, despite
the linker script trying to keep them.  The result is (eg):

`.exit.text' referenced in section `.alt.smp.init' of drivers/built-in.o: defined in discarded section `.exit.text' of drivers/built-in.o
`.exit.text' referenced in section `.alt.smp.init' of net/built-in.o: defined in discarded section `.exit.text' of net/built-in.o

This is the relevent part of the linker script (reformatted to make it
clearer):
| SECTIONS
| {
| /*
| * unwind exit sections must be discarded before the rest of the
| * unwind sections get included.
| */
| /DISCARD/ : {
| *(.ARM.exidx.exit.text)
| *(.ARM.extab.exit.text)
| }
| ...
| .exit.text : {
| *(.exit.text)
| *(.memexit.text)
| }
| ...
| /DISCARD/ : {
| *(.exit.text)
| *(.memexit.text)
| *(.exit.data)
| *(.memexit.data)
| *(.memexit.rodata)
| *(.exitcall.exit)
| *(.discard)
| *(.discard.*)
| }
| }

Now, this is what the linker manual says about discarded output sections:

|    The special output section name `/DISCARD/' may be used to discard
| input sections.  Any input sections which are assigned to an output
| section named `/DISCARD/' are not included in the output file.

No questions, no exceptions. It doesn't say "unless they are listed
before the /DISCARD/ section." Now, this is what asn-generic/vmlinux.lds.S
says:
| /*
|  * Default discarded sections.
|  *
|  * Some archs want to discard exit text/data at runtime rather than
|  * link time due to cross-section references such as alt instructions,
|  * bug table, eh_frame, etc. DISCARDS must be the last of output
|  * section definitions so that such archs put those in earlier section
|  * definitions.
|  */

And guess what - the list _always_ includes .exit.text etc.

Now, what's actually happening is that the linker is reading the script,
and it finds the first /DISCARD/ output section at the beginning of the
script. It continues reading the script, and finds the 'DISCARD' macro
at the end, which having been postprocessed results in another
/DISCARD/ output section. As the linker already contains the earlier
/DISCARD/ output section, it adds it to that existing section, so it
effectively is placed at the start. This can be seen by using the -M
option to ld:

| Linker script and memory map
|
|                 0xc037c080                jiffies = jiffies_64
|
| /DISCARD/
|  *(.ARM.exidx.exit.text)
|  *(.ARM.extab.exit.text)
|  *(.exit.text)
|  *(.memexit.text)
|  *(.exit.data)
|  *(.memexit.data)
|  *(.memexit.rodata)
|  *(.exitcall.exit)
|  *(.discard)
|  *(.discard.*)
|
|                 0xc0008000                . = 0xc0008000
|
| .head.text      0xc0008000      0x1d0
|                 0xc0008000                _text = .
|  *(.head.text)
|  .head.text     0xc0008000      0x1d0 arch/arm/kernel/head.o
|                 0xc0008000                stext
|
| .text           0xc0008200   0x2d78d0
|                 0xc0008200                _stext = .
|                 0xc0008200                __exception_text_start = .
|  *(.exception.text)
|  .exception.text
| ...

As you can see, all the discarded sections are grouped together - and
as a result of it being the first output section, they all appear before
any other section.

The result is that not only is the unwind information discarded (as
intended), but also the .exit.text, despite us wanting to have the
.exit.text preserved.

We can't move the unwind information elsewhere, because it'll then be
included even when we do actually discard the .exit.text (and similar)
sections.

So, work around this by avoiding the generic DISCARDS macro, and instead
conditionalize the sections to be discarded ourselves.  This avoids the
ambiguity in how the linker assigns input sections to output sections,
making our script less dependent on undocumented linker behaviour.

Reported-by: Rob Herring 
Tested-by: Mark Brown 
Signed-off-by: Russell King

ARM: vmlinux.lds: use _text and _stext the same way as x86

2011-07-07T22:36:34+00:00

x86 uses _text to mark the start of the kernel image including the
head text, and _stext to mark the start of the .text section.  Change
our vmlinux.lds to conform.  An audit of the places which use _stext
and _text in arch/arm indicates no users of either symbol are impacted
by this change.  It does mean a slight change to /proc/iomem output.

Acked-by: Nicolas Pitre 
Tested-by: Stephen Boyd 
Signed-off-by: Russell King

ARM: vmlinux.lds: move init sections between text and data sections

2011-07-07T22:36:31+00:00

Place the init sections between the text and data sections.  This
means all code is grouped together at the beginning of the kernel
image, and all data is at the end of the image.  This avoids problems
with the 24-bit branch instruction relocations becoming invalid with
large initramfs images.

Acked-by: Nicolas Pitre 
Tested-by: Stephen Boyd 
Signed-off-by: Russell King

ARM: vmlinux.lds: remove .rodata/.rodata1 from main .text segment

2011-07-07T22:36:28+00:00

RODATA() already handles these sections, so allow it to take care
of them for us.

Acked-by: Nicolas Pitre 
Tested-by: Stephen Boyd 
Signed-off-by: Russell King